public class LeetCode {
    public String longestPalindrome(String s) {
        int begin = 0,len = 0,n = s.length();
        for (int i = 0; i < n; i++) {
            //奇数长度
            int left = i,right = i;
            while(left>=0&&right<n&&s.charAt(left)==s.charAt(right)){
                left--;
                right++;
            }
            if(right - left - 1>len){
                begin = left+1;
                len = right - left - 1;
            }
            //偶数长度
            left = i;
            right = i+1;
            while(left>=0&&right<n&&s.charAt(left)==s.charAt(right)){
                left--;
                right++;
            }
            if(right - left - 1>len){
                begin = left+1;
                len = right - left - 1;
            }
        }
        return s.substring(begin,begin+len);
    }
}
